The invention relates to an operating mechanism for a folding top of a convertible with a hydraulic gear mechanism having a hydraulic pump and hydraulic motors connected in an articulated manner to the folding top, with a position transmitter for generating electric signals according to the position of the folding top and with control electronics for producing the intended sequence of movements of the folding top and for sensing the electric signals of the position transmitter.
Such operating mechanisms are frequently used in modern convertibles and are consequently known. In these cases, the hydraulic motors, usually designed as hydraulic cylinders, are controlled by means of electromagnetically switchable hydraulic valves. The limit switches are arranged at the ends of the range of movement of the folding top and, when the folding top reaches its end position, send a signal to the control electronics. In order to switch the hydraulic valves at the intended positions of the folding top, further limit switches are frequently arranged within the range of movement of the folding top. The speed of the folding top during opening and closing is dictated by the dimensions of the linkages of the folding top and the volumetric flow/delivery characteristic of the hydraulic pump. In these cases, even minor changes to the structural design of the folding top lead to distinct changes in the speed of movement of the folding top.
A disadvantage of the known operating mechanism is that the adaptation of the linkage to the intended speed of movement of the folding top is very complex. Furthermore, the movement of the folding top is very jerky and slow.